Rocna Anchor Failure

[Breaking Waves]

i have a tangental question . . . . if the bow part of a bow shackle (rather than the pin) is 'supposed' to be put thru the anchor shank slot, why don't the anchor manufacturers 1/4 round the edges of that slot to avoid point loading (and immediate rubbing off of the galvanizing)?

[Auspicious]

Originally Posted by Breaking Waves

i have a tangental question . . . . if the bow part of a bow shackle (rather than the pin) is 'supposed' to be put thru the anchor shank slot, why don't the anchor manufacturers 1/4 round the edges of that slot to avoid point loading (and immediate rubbing off of the galvanizing)?

It's a darn good question. Some of the older forged shank anchors like CQR had rounded slot edges. Even the Bruce anchors were square edged slots.

Rounded edges would galvanize better also. I can only assume the manufacturing savings overwhelm warranty issues.

Trying to think the process through rounding off the edges of the slot might require equipment (I'm thinking a vertical mill) that otherwise isn't necessary at all. That's a big cost.

My Rocna bower has a slot with squared edges. My secondary, also a Rocna, is a prototype of an anchor that never made it to market - it does have rounded edges on the slot. Probably hand work before being galvanized.

[double u]

“...good question. Some of the older forged shank anchors like CQR had rounded slot edges...“
Had 35, 45 & 60lbs CQR anchors-they had welded in big bow shackles, pin through anchorshank

[Breaking Waves]

Originally Posted by double u

Had 35, 45 & 60lbs CQR anchors-they had welded in big bow shackles, pin through anchorshank

I have done similar on some anchors - gotten a pretty huge bow shackle with the largest pin which fit thru the anchor shank slot, put it in place with red Loctite and a wrench and considered it a permanent part of the anchor (only removed when galvanizing anchor); and then the normal shackle with pin largest to fit thru chain bow to bow connected to this huge one.

In theory, it is still somewhat possible to sideways load the 'huge' shackle and reduce its strength by 50%. But this always looked more 'right' to my eye than the bow in the square-edged slot.

[alc]

Hi All,

I wanted to thank all those that provided helpful information about what might have happened to our anchor and what we could have done differently. I have gained some valuable knowledge about anchors, shackles and chains.

I have also seen how others have responded. Rocna has responded by saying I had the wrong anchor for our size boat. Their sizing chart says we should have a 20 kg anchor but they said since we are a multihull we should go up a size to 25 kg and then we should be conservative and go up another size to their largest, a 30 kg anchor. While this is good advice, bigger always being better, why don't they just say that is the required size needed for a boat our size and displacement, instead of providing a chart with inaccurate info.

Paragraph deleted.

I am ending my participation in this thread and am happy for all the new insights I have gained from those willing to help a newbie figure out the best way to keep my new anchor on board.

Safe sailing to all!!!

John

[CassidyNZ]

Originally Posted by Auspicious

It's a darn good question. Some of the older forged shank anchors like CQR had rounded slot edges. Even the Bruce anchors were square edged slots.

Rounded edges would galvanize better also. I can only assume the manufacturing savings overwhelm warranty issues.

Trying to think the process through rounding off the edges of the slot might require equipment (I'm thinking a vertical mill) that otherwise isn't necessary at all. That's a big cost.

My Rocna bower has a slot with squared edges. My secondary, also a Rocna, is a prototype of an anchor that never made it to market - it does have rounded edges on the slot. Probably hand work before being galvanized.

The sharp edges on most slots (anchors) are more modernly the result of being cut by laser or water jet then not being rounded over. As you say, the process/cost of rounding over is a significant part of the problem.

The thing is, if a shackle was used with the pin in the slot, the sharp edges would be less of a problem. But generally the correctly sized shackle will have a pin eye that doesn’t fit through the link on the chain so the pin end is used at the chain. That leaves the rounded end of the shackle fighting with the squared, sharp edge of the slot.

Whilst I have never used two shackles to connect anchor to chain (pin end in both chain and anchor) I have mused on the appropriateness of also having two rounded ends engaging with one another. I guess my resistance has its roots in having two things that can come loose.

I’m another anti-swivel proponent.

[alc]

Hi All,

I would like to apologize to everyone on the thread for allowing someone to suck me into posting like I have lately, there is no excuse and I should have remembered the lesson that all 5 year olds are taught. If you don't have anything nice to say than don't say anything at all.

I have picked up much knowledge for those who responded with helpful tips and broadened the discussion. With that being said I will no longer be following the thread.

Safe sailing to all and hopefully we will cross paths in the future.

John

[Pete7]

John, apology accepted.

I have cleaned up the last few posts in the thread since they quote e-mails from people at Rocna who naturally ask for more proof.

Pete

[daletournier]

Ok, I've been keeping my mouth shut but unless there was two catamarans that had their rocna shank break in or around Curacou the original story I heard direct from the owner was after a dragging incident the anchor was no longer there, this seems to differ from the story told here, both accusations involved the shank breaking, I was a skeptic then and are now.

[Old fella]

Originally Posted by daletournier

Ok, I've been keeping my mouth shut but unless there was two catamarans that had their rocna shank break in or around Curacou the original story I heard direct from the owner was after a dragging incident the anchor was no longer there, this seems to differ from the story told here, both accusations involved the shank breaking, I was a skeptic then and are now.

Damn!!! Something's a mis here, ( besides the anchor ) and something sounds a little weak, mabey the anchor, I'll stick to my danforth for now.

[daletournier]

I do not have a Rocna, BUT would not hesitate, they are well and truly proven, many world cruisers live every night hanging from one.

This anchor did not fail imho.

[double u]

Originally Posted by daletournier

Ok, I've been keeping my mouth shut but unless there was two catamarans that had their rocna shank break in or around Curacou the original story I heard direct from the owner was after a dragging incident the anchor was no longer there, this seems to differ from the story told here, both accusations involved the shank breaking, I was a skeptic then and are now.

...& now please come & clean up the mess here as I just blew my coffee all over the cockpit...!

[NorthernMac]

Originally Posted by Old fella

Damn!!! Something's a mis here, ( besides the anchor ) and something sounds a little weak, mabey the anchor, I'll stick to my danforth for now.

Looking at the construction of the stainless vulcan I got, to blow the end of that anchor out, that would take some crazy abuse, if I took a side by side with the vulcan against my Bruce and danforth, it’s substantial looking at the vulcan

Add to that how quick and well it sets, I’m quite happy with my rocna

If I had to drop in a area where I thought there was a reason to think I might not get the anchor back, I’d rather loose the danforth or Bruce well before the rocna vulcan, the thing rocks.

[Sojourner]

Originally Posted by NorthernMac

Looking at the construction of the stainless vulcan I got, to blow the end of that anchor out, that would take some crazy abuse, if I took a side by side with the vulcan against my Bruce and danforth, it’s substantial looking at the vulcan

Add to that how quick and well it sets, I’m quite happy with my rocna

If I had to drop in a area where I thought there was a reason to think I might not get the anchor back, I’d rather loose the danforth or Bruce well before the rocna vulcan, the thing rocks.

Have you been in a position to compare the rocna vulcan to the original? Ie did you upgrade? I've been thinking about doing so to get a 40kg anchor on my roller, as is the 33kg rocna is as big as I can go...

[NorthernMac]

Originally Posted by Sojourner

Have you been in a position to compare the rocna vulcan to the original? Ie did you upgrade? I've been thinking about doing so to get a 40kg anchor on my roller, as is the 33kg rocna is as big as I can go...

I’ve only had the vulcan